While an HR Certification gives you credibility and perhaps gives you another feather in your cap, it does not guarantee you will be successful in your HR Career. Basically it will help you get a job, but will not keep you there. The best part of getting your certification (some of my students would disagree) is the preparation part. This is when you gain additional insights on the HR profession.
Ultimately, if you are one of two finalists for a job and you have a certification and the other does not. If I were a betting man, and I am, I would bet on you....
So, get certified but do not rely on it!